NTSC television instruments having 16.times.9 aspect ratio picture tubes and format converters to convert 4.times.3 aspect ratio NTSC signals to a form suitable for display on a 16.times.9 display are now available. It therefore becomes desirable to have VCR tapes that play back signals electrically in the NTSC format but which were optically produced in a 16.times.9 aspect ratio. These signals may be produced by special lenses or by 16.times.9 CCD imagers. U.S. Pat. No. 4,897,722 (Flory), entitled WIDESCREEN TELEVISION TRANSMISSION SYSTEM UTILIZING CONVENTIONAL EQUIPMENT INCLUDING A CAMERA AND VCR, issued 30 Jan. 1990 (herein incorporated by reference), discloses a system in which a conventional NTSC format video camera utilizes an anamorphic lens to optically produce images in a 16.times.9 aspect ratio. That is, the anamorphic lens compresses the image horizontally by a factor of 4/3, which is the exact amount need to compensate for the expansion of a 4.times.3 aspect ratio NTSC image by a factor of 4/3 which automatically occurs when it is displayed on a wider 16.times.9 aspect ratio display screen.
If a such an optically-compressed NTSC video signal is played back to a standard 4.times.3 television receiver, the image would appear correct in height, but compressed in width, or "skinny". However, as noted above, a horizontal expansion of 4.times.3 aspect ratio signals occurs automatically when these signals are displayed on a 16.times.9 aspect ratio display screen because the time to scan a single horizontal line in both aspect ratios is the same. In other words, the same amount of video data is spread out over a greater distance in the same amount of time as the electron beam scans across the longer distance of the 16.times.9 aspect ratio display screen.
Unfortunately, if a standard 4.times.3 image is displayed on a 16.times.9 display screen, the same automatic horizontal expansion takes place, making everything appear "fatter". In order to prevent this undesirable display, the 4.times.3 image is typically displayed on the 16.times.9 display screen in its proper 4.times.3 aspect ratio, by displaying blank vertical bars on each side of the 4.times.3 image to fill up the remainder of the 16.times.9. International patent application PCT/US91/03746, filed 29 May 1991, published as WO 91/19397 on 12 Dec. 1991, (Willis), entitled SYNCHRONIZING SIDE BY SIDE PICTURES, (herein incorporated by reference) discloses a system in which a 4.times.3 image is "speeded up" to enable the video data to be read out at a faster rate and avoid the appearance of stretching.
Clearly, a 16.times.9 aspect ratio television receiver should be able to properly display the optically-compressed 16.times.9 NTSC signals over the entire expanse of the wide-screen, and properly display the 4.times.3 video signals in a 4.times.3 aspect ratio with accompanying blank vertical bars. A problem exists in that an optically-generated 16.times.9 compressed NTSC video signal is indistinguishable from a standard 4.times.3 NTSC video signal, because it is the image content of the signal which changes; not its format which is the standard NTSC format in both cases. Thus, there is no way to examine the video signal stream and automatically direct the television receiver which way to display the image (i.e., 16.times.9, or 4.times.3 with blank bars)